The invention relates to a belt conveyor for transferring a web threading tail in a web manufacturing machine, and to a method for changing the belt loop of a belt conveyor for a web threading tail in a web manufacturing machine.
WO publication No. 03018909 discloses a belt conveyor having a frame construction and at least two pulleys or rolls therein, a belt loop arranged around the rolls, and adjustment elements arranged in connection with the frame construction and at least one of the rolls for adjusting the belt loop tension by changing the relative position of the rolls. In the proposed tail threading device as well as in the other known tail threading devices based on a belt loop, the belt loop is tensioned on both sides of the frame construction. In other words, both ends of the roll are moved separately. For this, between the frame construction and the roll, there are adjustment elements, which are usually based on bolt tensioning and fastening.
In practice, the belt conveyor is located in the vicinity of rotating or otherwise moving machine parts for transferring the web threading tail from one machine section to another. A belt loop that is usually formed of an air permeable fabric needs to be changed from time to time, whereat at least one of the rolls must be moved by means of the adjustment elements. Reaching to the tensioning and fastening bolts is difficult in a fixedly mounted belt conveyor. This is the case in particular as regards the bolts located on the outermost side of the frame construction. Consequently, changing the belt loop is slow and difficult, often even dangerous. Furthermore, the operation of the adjustment elements and an accurate positioning of the roll are difficult. In practice, the rolls must additionally be aligned such that the belt loop keeps in place on top of the frame construction. An incorrectly positioned roll leads to belt conveyor malfunctions as well as to rapid belt loop wear and even damage.